This invention relates generally to a technique for sealing the closure cap of a manually operated dispenser to a container, utilizing a liner of hot melt material.
Manually actuated dispensers, such as the fingertip actuated and the trigger actuated types, are mounted on the neck of a container utilizing a closure cap coupled to the dispenser. A separate liner or gasket of elastomeric material, such as polyethylene, isobutylene/polyethylene or foamed polyethylene, is typically provided for sealing the package from leakage of product from the container along a path between the neck rim and the lower end of the dispenser. The liner is positioned between the neck rim and an annular surface at the lower end of the dispenser, and is press-fitted, snap-fitted or otherwise engaged with the dispenser at its lower end for retaining the gasket in place prior to assembly with the container.
The closure cap may be internally threaded for engagement with the external threads of the container neck. On tightening the closure, i.e., "torquing down", the tightened closure cap oftentimes has the tendency to back-off or loosen, especially during shipment and storage, thereby causing leakage of product from the container. For example, vibrations during shipment can cause the closure cap to loosen as the compressed gasket seal slips and relaxes. Likewise, should the dispenser body reorient itself on the container during shipment or packaging or handling prior to shipment, torque back-off has been experienced upon turning movement of the dispenser body about the central axis of the container in a loosening direction. Moreover, if the dispenser body is reoriented during use relative to the container by turning in a loosening direction, the closure cap tends to back-off, causing leakage.
Otherwise, the metallic closure cap may be swaged on to the container neck for coupling the cap to the container by deforming the cap during a swaging process. The separate gasket liner used oftentimes proves ineffective for its intended sealing purpose if the liner is too hard and/or if the cap is not carefully swaged in place.
The selection of different liners for their relative softness and hardness depending on the closure cap style, container size and use, product compatibility, dispenser size and style, etc., renders it difficult for the dispenser supplier to meet all the needs of its customers.
Moreover, during shipment and handling separate gaskets easily fall away from the dispenser package to which they are attached, are costly to manufacture and assemble, and present handling problems during assembly and storage.
Integral liners have been provided to avoid gasket fallout from the dispenser body. Such liners are molded as part of the body and of the same Plastic material, thereby limiting the integral liner to the choice of dispenser body material. A soft or tacky liner is therefore not made possible with this approach.